Low boiling hydrocarbon oils



15 that the principles 30 described Patented Mar. 23, 1937' UNITED STATES PATENT JOFFlCE a 2,014,401 I :32:1- to Standard Oil Development poration of Delaware No Drawing.

Company, a cor-- Application January s, 1931,

Serial no. 1.525

'5 Claims. The present invention relates to improved hydrocarbon oils which have been made stable against gum form tion bythe addition of small e amounts of para diamlno aryl compoundsor para ,5 amino phenolic understood from the following description:

It has long been well known in the petroleum industry that low boiiing'hydrocarbon oils such as gasoline and naphtha, especially cracked 89,8 line and naphtha, often contain gum or gum forming constituents in harmful quantity; In the following description, the oil tobe treated will be referred to as low oil or naphtha. It is to be understod, however,

'of the invention may be apanalogous character.

plied to other oils of Naphthas containing large quantities of gum, or constituents tending to form gum during storage,'are objectionable for many purposes, such as 'for motor fuels, light solvents, etc. Recently a careful studyof gum formation has been made by petroleum chemists, and several organic compounds have been found-which, when added in small quantities to low boiling hydrocarbon oil, will retard or inhibit gum formation for periods of time varying with the nature of the compound, the oll, and otherconditions. The usual testfor such gum forming constituents is known as-the copper dish method and is of Mines Technical Paper No. 323 D, revised October 21, 1927. The result of this test is expressed in milligrams of gum left in the dish on evaporation of 100 cc. of naphtha. Another testing; method consists oxygen under pressure to the sample of the low boiling hydrocarbon oil. to be tested in a closed vessel, and then keeping the oil at elevated temperature of say 100 C. 40 of say 100 lbs. per square inch. For a certain time the pressure remains practically constant,

then it begins to drop suddenly. observed on a pressure gage. The period of time during which no pressure drop is observed is-called the induction period. The longer this induction period, the better is the particular oil tested," and the less likely it is to form gumdurlng storage.

An approximate quantitative relation for the gum inhibiting power of.a certaininhibitor may be expressed by the following equation:

' S-B- l I. PJ-TXE Pl=inlnbiting power where I. r v S=induction period of solution B=induction period of blank or solvent- C=conoentration of the by weight.

00 The test just described is quicker and more inhibitor in compounds, and it will be fully boiling hydrocarbon I v as alkyl or aryl group. Such on page 96 of the United States Bureau of adding under a-pressure of oxygen This drop ismy intention to (cu l-9) reliableand gives more readily reproducible data,

than the copper dish method. The I. P. number of an inhibitor will accordingly be used herein as a measure of its value. It will be understood, however, that the inhibitors vention may be rated according to the'copper ofthe present in- I dish method, or other suitable method, and will show a corresponding value. Moreover, these inhibitors are effective in actual storage tests, that is, when added to naphtha stored in the tanks of refineries or distributors. The oxidation test describedherein gives an accelerated indication of the performance to be expected during storage.

I have discovered 'thatcompounds having av benzene ring containing'two amino'grotll or anamin'o and a hydroxyl group, in the para position, .are powerful gum inhibitors. The simplest typesof such compounds are para phenylene diamine, para amino phenol, and their hom'ologues in which one or more hydrogen 'atoms of the benzene ring are substituted by an an aryl or a cycloparaflinic group.

One or both hydrogen group or groups may be substituted, for example, by the introduction of .a hydrocarbon group such alkylation' increases the solubility of the compound to the number of carbon atoms in the alkyl radical, and the alkylated products often have anon-alkylated products due preference over the to this increase of solubility.

Compoundsof the class 'give an efllcient protection against-gum formation in'a gasoline long period of time when added in .amountsof from 0.0005 to 0.1%- by Weight 01 the 011. Thenecessary amounts areibest determined em pirically. Compounds of the type described are -in general sufliciently oil soluble and may be readily distributed large bodies of oil by simple mixing. If desirable they may be dissolved in benzene or other suitable solvent from which they will not be readily precipitated byaccess of moisture. The solution so prepared may be mixed with the given the names of some individual members of .the'typeof compounds which are comprised in the present invention to para phenylene 'gether with their I. P. numbers: diamine with an I. P. -numberof 2,000, para amino phenol with an I.

amylated (secondary). para amino phenol with an I. P. number of over' 1,000.

My invention is not to be limited by any thecry nor by the examples given but only by the following claims in. which it is claim all novelty inherent in myinvention: .1

described wove will during ordinary storage for a uniformly throughout even.

P. number of 1,000,

in oils according as illustrations I claim: ino phenol in which one of the amino hydrogens 1. A low-boiling hydrocarbon oil normally has been substituted by an amyl group. tending to deteriorate and form gum during 4. Product according to claim 3, in which the storage, containing a small amount of an amino amino phenol contains a secondary amyl group.

5 phenol in which at least one of the amino hydro- 5. A method of stabilizing a low-boiling hydro- 5 gens has been substituted byan alkyl radical carbon oil tending to deteriorate and form a and the substituted amino group contains at least gum during storage, which comprises adding five carbon atoms, 'said gum inhibitor havingthereto a small amount of an amino phenol in solubility and inhibiting power of the order of which at least one of the amino hydrogens has 10 those of an amylated amino phenol, in quantity been substituted by an alkyl radical and the 10 suflicient to retard such gum formation. substituted 'amino group contains at least five 2. Product according to claim 1 in which only carbon atoms, said gum inhibitor having soluone amino hydrogen has been substituted by an bility and inhibiting power of the order of those alkyl radical. of an amylated amino phenol, in quantity sum- 15 3. A cracked gasoline normally tending to decient to retard such gum formation. 15 I teriorate and form gum during storage, contain- I ing about .0005 to 0.1% by weight of a para am- CARLOS L. GUTZEI T. 

